The quantitative relationship between out diameter (O.D.) and thickness of hollow glass microspheres (HGM) made by liquid droplet method is given. The operation conditions, such as distributions of temperature and purge gas velocit y in the furnace, concentrations of solution, and the operation conditions of th e droplet generator, are experimentally optimized, under which HGM is produced with O.D. of 300~450μm, wall thickness of 0.7~1.2μm, aspect ratio of 300~700, surface roughness better than 10nm, concentricity better than 97%, sphericity higher than 99%, and out and inner failure pressures more than 0.91MPa and 0.43MPa respectively.